1. Technical Field
The present invention relates to a virtual image display apparatus which presents a video image formed by an image display element and the like to a viewer, and particularly to a virtual image display apparatus which is preferably applied to a head mount display designed to be mounted on the head of the viewer.
2. Related Art
Various optical systems to he embedded in a virtual image display apparatus such as a head mount display (hereinafter, also referred to as an HMD) designed to be mounted on the head of a viewer have been proposed. For example, an optical system which displays a virtual image and enables viewing of an external image by using a video image optical system including an image display element and the like and a relatively thick prism member arranged in front of the eyes is known (see JP-A-2013-200553, for example).
In the case of the virtual image display apparatus using the prism member as described above, it is not easy to achieve a decrease in thickness and weight while implementing an optical system including the video image optical system and the prism member, which can be fitted to a face surface, due to restriction of optical design. If priority is placed on the decrease in thickness, a degree of freedom in design is limited.
In contrast, it is also possible to consider that the shape of the prism member is set to a simple plate shape. However, it is not easy to achieve the decrease in thickness and weight while implementing the entire system which can be fitted to the face surface.